Curable thermoset resin composition

ABSTRACT

A curable composition including a thermoset resin a curing agent component, an amount of a thermoplast component having reactive pendant and/or end groups, an organometallic curing catalyst component. The organometallic curing catalyst component is capable of forming cross-links with reactive pendant and/or end groups of the thermoset and thermoplast resins and comprises an organometallic complex compound of the formula I=M(R) n , where M is selected from titanium, zirconium, hafnium, cerium, vanadium, niobium, R is selected from mono-, bi- and tri and/or tetra dentate organic ligands and n is four or six.

The present invention relates to improvements relating to resincompositions, in particular relating to curable thermoset resincompositions, such as epoxy resin compositions, by the provision of asuitable curing means, to the process for the preparation of suchcurable resin compositions and to the cured products thereof.

Thermoset resins, or thermosets, are characterised by their temperaturestability, induced in the curing stage by the onset of cross-linking.The resistance of this product to further application of heat (up tocharring point) makes it eminently suitable for a wide number ofapplications, typically as structural plastics, laminates, surfacecoatings and adhesives. Additionally, the structural nature of theseresins render them with excellent properties of mechanical andelectrical strength and chemical resistance. The resins are additionallycharacterised by a low shrinkage on polymerisation.

It is common practice to incorporate a certain amount of a thermoplasticcomponent in curable thermoset resins to induce additional properties oftoughness and ductility and solvent resistance which extends the usefulrange of these products.

Conventional thermosets include the phenolics, aminoplastics, epoxys andsome polyurethanes. Despite their wide range of usefulness, these resinsare all characterised by a high processing cost, induced by therequirement for a high curing temperature in order to initiate thecross-linking stage of the curing process, commonly known as thepost-curing stage. In European patent application no. EP-A-0 311 349 inthe name of ICI Composites Inc are described epoxy resins requiring acuring temperature of the order of 180° C. or more, with the inclusionof a catalyst, in particular, curable resin compositions comprising athermoset resin component, together with a thermoplastic resin componentfor property modification, and a poly aryl sulphone curing agent. Thecurable resins typically pass through a glass transition temperature at120° C. but require elevated temperatures of 180° C. or more forpost-curing, to raise the glass transition temperature (Tg). Typicallycuring is carried out at elevated pressure in the region of 3 to 7 bar,requiring the use of an autoclave or the like, increasing further bothequipment and operation costs.

Whilst it is true that a lower than optimum temperature may be employed,this requires increase in cure time and the possibility thatcross-linking may nevertheless not be absolute or that properties may beotherwise compromised, and nevertheless delivers little or no economicsaving due to maintaining the selected temperature for a prolongedperiod. In industrial application, this is moreover significant sincethe productivity would be significantly reduced were it necessary tocure thermoset products for up to 18 hours, moreover taking up valuableautoclave time.

In certain applications thermoset resins are employed for thepreparation of products which are to be produced in limited number as“designer” products, or intended for a small specialist market, or forthe preparation of products which have a limited life cycle, not byvirtue of their physical or mechanical integrity, but rather by virtueof changes in market demands and renewal of appearance or design. Thisis a severe limitation of the commercial potential of such products,since the high processing temperatures employed for their preparationnecessitate the use of high temperature resistant moulds or tools wheresuch products are made by means of moulding processes. It would bereadily apparent that the most temperature resilient tools which areable to maintain their moulding integrity at the required temperaturesin excess of 180° C., are typically constructed of metals and as suchare expensive to commission and will be required to pay back over arelatively long period of time. This is particularly the case forexample, for the manufacture of panels such as for use in the specialistaerospace industry or in the construction of vehicle, caravan, mobilehome or motorbike body shells or the like which are typically subject tofluctuating demands of fashion induced by severe competition, and oftechnology demanding changes in body shell shape for improvedstream-lining, road holding, compatibility with other technicalcomponents, weight reduction and the like. Application to otherproducts, for example for use in the construction of composite furnituresuch as household, office or garden items is also envisaged, for theabove reasons.

Accordingly, there is need for a curable thermoset resin which may becured at a temperature which is less than that corresponding to themaximum temperature resistance of a suitable composite material whichmay be employed as a mould and which mould is required to serve for onlya limited number of products and/or a limited lifetime. Moreover thereis a need for such curable thermoset resin for the preparation ofcomposite objects or products at low industrial processing cost.Moreover there is a need in some applications for such curable thermosetresin for the preparation of composite objects or products which areunmodified in respect of their mechanical and physical properties byvirtue of the modified curable resin and accordingly are able to meetthe demands to which the products will be subjected, for example forapplication in the manufacture of panels as hereinbefore described andin particular aerospace product, racing car, motor car and motorbikepanels which must be able to perform to a high level of reliability interms of mechanical and physical properties.

We have now surprisingly found a resin composition and a process for thepreparation thereof which meet the above mentioned requirements inadmirable manner, specifically by means of incorporation of a certainclass of compounds within a curable thermoset resin composition, whichcompounds enable the curing at reduced temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 illustrate the morphology of an example of the presentinvention.

There is therefore provided, in its broadest aspect, according to thepresent invention a curable composition comprising:

(a) a thermoset resin component;

(b) a curing agent component;

(c) an amount of a thermoplast component; and

(d) an organometallic curing catalyst component.

Reference herein to components a), b), c) and/or d) is to the activemonomer compound, partially cured resin precursor, oligomer or the like,to the functionally protected inactive equivalent or to any formcommonly employed in the art. The properties of the invention may beevident in the curable composition but are normally evident only in thecured form thereof.

It will be appreciated that Component a) may be suitably selected fromthe group consisting of an epoxy resin, an addition-polymerisationresin, especially a bis-maleimide resin, a formaldehyde condensateresin, especially a formaldehyde-phenol resin, a cyanate resin, anisocyanate resin and mixtures of two or more thereof, and is preferablyan epoxy resin derived from the mono or poly-glycidyl derivative of oneor more of the group of compounds consisting of aromatic diamines,aromatic monoprimary amines, aminophenols, polyhydric phenols,polyhydric alcohols, polycarboxylic acids and the like, or a mixturethereof. Examples of addition-polymerisation resins are acrylics,vinyls, bis-maleimides, and unsaturated polyesters. Examples offormaldehyde condensate resins are urea, melamine and phenols.

More preferably the Component a) comprises at least one epoxy resinprecursor, which is liquid at ambient temperature for example asdisclosed in EP-A-0 311 349 or in PCT/GB/95/01303, selected fromN,N,N′N′-tetraglycidyl diamino diphenylmethane (eg “MY 9663”, “MY 720”or “MY 721” sold by Ciba-Geigy) viscosity 10-20 Pa s at 50° C.; (MY 721is a lower viscosity version of MY720 and is designed for higher usetemperatures);N,N,N′,N′-tetraglycidyl-bis(4-aminophenyl)-1,4-diiso-propylbenzene (egEpon 1071 sold by Shell Chemical Co) viscosity 18-22 Poise at 110° C.;N,N,N′,N′-tetraglycidyl-bis(4-amino-3,5-dimethylphenyl)-1,4-diisopropylbenzene,(eg Epon 1072 sold by Shell Chemical Co) viscosity 30-40 Poise at 110°C.; triglycidyl ethers of p-aminophenol (eg “MY 0510” sold byCiba-Geigy), viscosity 0.55-0.85 Pa s at 25° C.; preferably of viscosity8-20 Pa at 25° C.; preferably this constitutes at least 25% of the epoxycomponents used; diglycidyl ethers of bisphenol A based materials suchas 2,2-bis(4,4′-dihydroxy phenyl) propane (eg “DE R 661” sold by Dow, or“Epikote 828” sold by Shell), and Novolak resins preferably of viscosity8-20 Pa s at 25° C.; glycidyl ethers of phenol Novolak resins (eg “DEN431” or “DEN 438” sold by Dow), varieties in the low viscosity class ofwhich are preferred in making compositions according to the invention;digylcidyl 1,2-phthalate, eg GLY CEL A-100; diglycidyl derivative ofdihydroxy diphenyl methane (Bisphenol F) (eg “PY 306” sold by CibaGeigy) which is in the low viscosity class. Other epoxy resin precursorsinclude cycloaliphatics such as3′,4′-epoxycyclohexyl-3,-4-epoxycyclohexane carboxylate (eg “CY 179”sold by Ciba Geigy) and those in the “Bakelite” range of Union CarbideCorporation.

The Component a) is suitably the product of at least partly curing aresin precursor using a curing agent and optionally a catalyst.

The Component b) is suitably selected from any known curing agents, forexample as disclosed in EP-A-0 311 349 or in PCT/GB95/01303, which areincorporated herein by reference, such as an amino compound having amolecular weight up to 500 per amino group, for example an aromaticamine or a guanidine derivative. Particular examples are 3,3′- and4-,4′-diaminodiphenylsulphone, (available as “DDS” from commercialsources), methylenedianiline,bis(4-amino-3,5-dimethylphenyl)-1,4-diisopropylbenzene (available asEPON 1062 from Shell Chemical Co);bis(4-aminophenyl)-1,4-diisopropylbenzene (available as EPON 1061 fromShell Chemical Co); 4-chlorophenyl-N,N-dimethyl-urea, eg Monuron;3,4-dichlorophenyl-N,N-dimethyl-urea, eg Diuron and dicyanodiamide(available as “Amicure CG 1200 from Pacific Anchor Chemical). Such aminecuring agents are additional to the Component c) if such is anamine-ended thermoplast; thus the composition preferably containsepoxy-reactive amines of two types, one having a molecular weight up to500 per amine group, the other having a molecular weight of at least5000 per amine group and the total amine content being in the range70-110% of the stoichiometric requirement of the epoxy resin precursor.Other standard epoxy curing agents such as aliphatic diamines, amides,carboxylic acid anhydrides, carboxylic acids and phenols can be used ifdesired.

Conventionally, and as described in EP-A-0 311 349 or in PCT/GB95/01303,a catalyst for the epoxy resin component/curing agent reaction may alsobe used, typically a Lewis acid or a base. According to the presentinvention however it is convenient to dispense with such catalyst and inplace thereof to employ a component d) as hereinbefore defined.

The Component c) suitably comprises at least one thermoplastic polyarylsulphone component, for example as defined in EP-A-0- 311 349,comprising at least one polyaryl sulphone comprising ether-linkedrepeating units, optionally additionally comprising thioether-linkedrepeating units, the units being selected from the group consisting of

—(PhSO₂Ph)_(n)—

and optionally additionally

—(Ph)_(a)—

wherein Ph is phenylene, n=1 to 2 and can be fractional, a=1 to 3 andcan be fractional and when a exceeds 1, said phenylenes are linkedlinearly through a single chemical bond or a divalent group other than—SO₂— or are fused together, provided that the repeating unit—(PhSO₂Ph)_(n)— is always present in said at least one polyarylsulphonein such a proportion that on average at least two of said units—(PhSO₂Ph)_(n)— are in sequence in each polymer chain present, said atleast one polyarylsulphone having reactive pendant and/or end groups offormula —A′—Y where A′ is a divalent hydrocarbon group and Y is a groupselected from groups providing active hydrogen, epoxy, cyanate,isocyanate, vinyl, allyl, ethynyl and maleimide functionality.

Preferably the polyarylsulphone component comprises polyether sulphone,more preferably a combination of polyether sulphone and of polyetherether sulphone linked repeating units, in which the phenylene group ismeta- or para- and is preferably para, and wherein the phenylenes arelinked linearly through a single chemical bond or a divalent group otherthan sulphone, or are fused together. By “fractional” reference is madeto the average value for a given polymer chain containing units havingvarious values of n or a.

Additionally, as also discussed, in said at least one polyarylsulphone,the relative proportions of the said repeating units is such that onaverage at least two units (PhSO₂Ph)_(n) are in immediate mutualsuccession in each polymer chain present and is preferably in the range1:99 to 99:1, especially 10:90 to 90:10, respectively. Typically theratio is in the range 25-50 (Ph)_(a), balance (Ph SO₂Ph)_(n). Inpreferred polyarylsulphones the units are.

1 X Ph SO₂ Ph X Ph SO₂ Ph (“PES”) and

11 X (Ph)a X Ph SO₂ Ph (“PEES”)

where X is O or S and may differ from unit to unit; the ratio of 1 to 11(respectively) preferably between 10:90 and 80:20 especially between10:90 and 55:45.

The preferred relative proportions of the repeating units of thepolyarylsulphone may be expressed in terms of the weight percent SO₂content, defined as 100 times (weight of SO₂)/(weight of average repeatunit). The preferred SO₂ content is at least 22, preferably 23 to 25%.When a=1 this corresponds to PES/PEES ratios of at least 20:80,preferably in the range 35:65 to 65:35.

The above proportions refer only to the units mentioned. In addition tosuch units the polyarylsulphone may contain up to 50 especially up to25% molar of other repeating units: the preferred SO₂ content ranges (ifused) then apply to the whole polymer. Such units may be for example ofthe formula.

in which A is a direct link, oxygen, sulphur, —CO— or a divalenthydrocarbon radical. When the polyarylsulphone is the product ofnucleophilic synthesis, its units may have been derived for example fromone or more bisphenols and/or corresponding bisthiols or phenol-thiolsselected from hydroquinone, 4,4′-dihydroxybiphenyl, resorcinol,dihydroxynaphthalene (2,6 and other isomers),4,4′-dihydroxybenzophenone, 2,2′-di(4-hydroxyphenyl) propane and-methane.

If a bis-thiol is used, it may be formed in situ, that is, a dihalide asdescribed for example below may be reacted with an alkali sulphide orpolysulphide or thiosulphate.

Other examples of such additional units are of the formula

in which Q and Q′, which may be the same or different, are CO or SO2; Aris a divalent aromatic radical; and n is 0, 1, 2, or 3, provided that nis not zero where Q is SO2. Ar is preferably at least one divalentaromatic radical selected from phenylene, biphenylene or terphenylene.Particular units have the formula.

where m is 1, 2 or 3. When the polymer is the product of nucleophilicsynthesis, such units may have been derived from one or more dihalides,for example selected from 4,4′-dihalobenzophenone, 4,4′bis(4-chlorophenylsulphonyl)biphenyl, 1,4 bis(4-halobenzoyl)benzene and4,4′-bis(4-halobenzoyl)biphenyl.

They may of course have been derived partly from the correspondingbisphenols.

The polyarylsulphone may be the product of nucleophilic synthesis fromhalophenols and/or halothiophenols. In any nucleophilic synthesis thehalogen if chlorine or bromine may be activated by the presence of acopper catalyst. Such activation is often unnecessary if the halogen isactivated by an electron withdrawing group. In any event fluoride isusually more active than chloride. Any nucleophilic synthesis of thepolyarylsulphone is carried out preferably in the presence of one ormore alkali metal carbonates in up to 10% molar excess over thestoichiometric and of an aromatic sulphone solvent, at a temperature inthe range 150-350° C.

If desired, the polyarylsulphone may be the product of electrophilicsynthesis.

As previously mentioned, said at least one polyarylsulphone contains endgroups and/or pendant groups of formula —A′—Y where A′ is a divalenthydrocarbon group, preferably aromatic, and Y is a group reactive withepoxide groups or with a curing agent or with like groups on otherpolymer molecules. Examples of Y are groups providing active hydrogenespecially OH, NH₂, NHR or —SH, where R is a hydrocarbon groupcontaining up to 8 carbon atoms, or providing other cross-linkingreactivity especially epoxy, cyanate, isocyanate, acetylene or ethylene,as in vinyl, allyl or maleimide.

The number average molecular weight of the polyarylsulphone is suitablyin the range 2000 to 60000. Preferably it is over 9000 especially over10000 for example 11000 to 25000 and structurally as well as by chemicalinteraction increases toughness by comparison with that of the thermosetresin alone by providing zones of the tough thermoplast betweencross-linked thermoset zones. Another useful sub-range is 3000-11000,especially 3000-9000 in which it acts more as chain-extender for thethermoset resin, separating and diluting local cross-links and thustoughening the structure. Within the above definition of thepolyarylsulphone those are preferably chosen which are miscible withsuitable epoxy resin precursors, have high modulus and Tg and are tough.

The weight proportion of thermoplast component in the composition istypically in the range 5 to 90%, especially 20 to 50, for example 25 to40%.

The Component d) is suitably selected from organometallic compositionsor compounds which are capable of forming cross-links with reactivependant and/or end groups, such as the epoxy or hydroxy groups of thethermoset resins and the groups A′Y of the thermoplast resins, andsuitably are of reactivity adapted for the advancement of the resincomposition of the invention only when subjected to the desiredconditions of elevated temperature. Preferably the Component d)comprises a class of organometallic complex compounds represented by theformula I:

M(R)_(n)  (I)

wherein M is any suitable metal able to support organic ligands, R isselected from known mono-, bi- and tridentate organic ligands and n isthe coordination number of the metal, and active intermediates orcombination products thereof. Suitably M is selected from the transitionelements and the lanthanides, preferably from titanium, zirconium,hafnium, cerium, vanadium, niobium, more preferably from titanium andzirconium, whereby n is four or six.

Suitably R is selected from organic ligands comprising one or morenucleophilic units or moieties, for example selected from straight orbranched, short or long chain alcohols, amines, acids, esters,phosphates, ketones, anhydrides or the like which may optionally beadditionally functionalised, and combinations thereof in the form ormono, bi, tri and/or tetradentate ligands, suitably of a combination ofmonodentate ligands with one or more bi, tri or tetradentate ligands,which multidentate or chelate ligands for example are suitably selectedfrom glycols, alkanolamines, alpha-hydroxy acids, β-keto-esters and acidphosphates and combinations thereof. In a preferred embodiment theComponent d) comprises an organo titanate wherein two of the organicligands comprise monodentate ligands such as alcohols and a further twocomprise bidentate chelate ligands as hereinbefore defined, however theligands may be present in any combination of multiplicity and type.

The component d) may comprise at least in part, an amount of compound offormula I as hereinbefore defined which has been pre-reacted to formmultinuclear complex, oligomeric or combination products.

Organo titanates are known, and commercially available for example fromTioxides Specialities Limited, and are used in a number of applicationsin the manufacture and modification of synthetic and natural products.The wide range of application of such compounds is however coupled witha wide range of effects, whereby it is not possible to predict thenature or effect thereof on specific systems without resorting todetailed experimentation. According to the present invention it hassurprisingly been found that the incorporation of component d) insuitable manner, and in particular comprising an organotitanate ashereinbefore defined may enable the curing of the hereinbefore definedthermoset resin composition at significantly lowered temperature, andadvantageously in a preferred aspect with no deleterious effect on themechanical and physical properties thereof. In a particularly preferredaspect of the invention certain organotitanates enable the preparationof a thermoset resin as hereinbefore defined having morphologiessuperior to the corresponding resin which is prepared in absence of theorganotitanate.

In a particularly advantageous aspect of the present invention theorganometallic component d) may be selected for its specificapplication, either by virtue of the nature of Components a), b) and c)as hereinbefore defined or by virtue of the required processingtemperature, processing time, mechanical or physical properties or thelike which are desired.

Preferably therefore there is provided according to the presentinvention a thermoset resin composition as hereinbefore definedcomprising the components a), b) and c) as hereinbefore defined and acomponent d) wherein component d) comprises one or more organotitanatesrepresented by the formula II:

Ti(R′)₄  (II)

wherein R′ is selected from organic ligands as hereinbefore defined withreference to R, and suitably is selected from ligands comprisingprimary, secondary and tertiary C₂-C₁₈ moieties, for example comprisingn- or i-propyl, n-, i- or t- butyl, pentyl, hexyl, heptyl or octylmoieties, and active intermediates or combination products thereof.

In a particularly preferred aspect of the invention, the compound offormula II as hereinbefore defined comprises one or more monodentateligands selected from alcohols and amines as hereinbefore definedoptionally in combination with one or more bidentate ligands selectedfrom glycols, alcohol amines, alphahydroxy acids, β-ketone esters andacid phosphates as hereinbefore defined. Preferably any ligand comprisesa suitable carbon chain link of the order C₂-C₁₈ as hereinbefore definedwhich is compatible with the other components of the composition and thedesired rigidity of cross-linking.

Preferably the component d) is present, calculated as the active resinwithout any added solvent or the like, in an amount of up to 15 parts byweight, preferably in excess of 0.5 parts by weight, for example in therange of 1 to 12 parts by weight, and most preferably in the range of 3to 10 parts by weight with respect to the total weight of the componentsa) to c). The amount of component d) will be determined by the nature ofthe components a), b) and c) with which it may cross-link and by theparticular component d), for example an organo titanate being employed.

In a particularly advantageous aspect of the invention thermoset resinscomprising an amount of thermoplast component as taught in EP-A-0 311349 having excellent morphological properties, typically comprising afine co-continuous morphology, are also obtained with the use of certaincomponents d) as hereinbefore defined.

Moreover other properties such as the glass transition temperature, andmechanical properties of yield stress, modulus, ductility and the likemay be advantageously enhanced according to the present invention. Inparticular it has been found that the composition comprising componentd) as hereinbefore defined wherein at least one and preferably two ofthe groups R comprise a strongly nucleophilic chelate ligand, and mostspecifically comprise two or more ligands selected from chelates alcoholamine, β-keto-acids, -esters and -ketones and the like, provide curedproducts having excellent mechanical and physical properties.

The components a) to d) as hereinbefore defined are commerciallyavailable, or the preparation of components a) to c) is taught inhereinbefore mentioned EP-A-0 311 349 and or in PCT/GB95/01303.

The component d) as hereinbefore defined is suitably obtained forexample from the commercially available tetrachloro compound, by meansof the substitution reaction with an alcohol and substituting further asappropriate. In fact the compounds n-propyl, isopropyl and n-butyltitanate are industrially manufactured, whereby the preparation of thedesired component d) is suitably performed by means of the followingreaction:

Ti(O—iC₃H₇)₄+4ROH→Ti(OR)₄+4iC₃H₇OH

wherein R is as hereinbefore defined with reference to component d).

In a further aspect of the invention there is provided a composition foruse in the curing of thermoset resins as hereinbefore defined withreference to components a), b) and c) comprising an organometalliccompound as hereinbefore defined with reference to component d).

In a further aspect of the invention there is provided the use ofcompound of formula I as hereinbefore defined, in the preparation of acomponent d) as hereinbefore defined for the curing ofthermoplast-modified thermoset resins as hereinbefore defined.

In a further aspect there is provided according to the invention the useof a precursor or intermediate in the preparation of a compound of theformula I as hereinbefore defined for the preparation of a compound d)as hereinbefore defined for the curing of thermoplast-modified thermosetresins compositions as hereinbefore defined.

The composition is particularly suitable for fabrication of structures,including load-bearing or impact resisting structures. For this purposeit may contain a reinforcing agent such as fibres. Fibres can be addedshort or chopped typically of mean fibre length not more than 2 cm, forexample about 6 mm. Alternatively, and preferably, the fibres arecontinuous and may, for example, be unidirectionally-disposed fibres ora woven fabric, ie the composite material comprises a prepreg.Combinations of both short and/or chopped fibres and continuous fibresmay be utilised. The fibres may be sized or unsized. Fibres can be addedtypically at a concentration of 5 to 35, preferably at least 20%, byweight. For structural applications, it is preferred to use continuousfibre for example glass or carbon, especially at 30 to 70, moreespecially 50 to 70% by volume.

The fibre can be organic, especially of stiff polymers such as polyparaphenylene terephthalamide, or inorganic. Among inorganic fibresglass fibres such as “E” or “S” can be used, or alumina, zirconia,silicon carbide, other compound ceramics or metals. A very suitablereinforcing fibre is carbon, especially as graphite. Graphite fibreswhich have been found to be especially useful in the invention are thosesupplied by Amoco under the trade designations T650-35, T650-42 andT300; those supplied by Toray under the trade designation T800-HB; andthose supplied by Hercules under the trade designations AS4, AU4, IM 8and IM 7.

Organic or carbon fibre is preferably unsized or is sized with amaterial that is compatible with the composition according to theinvention, in the sense of being soluble in the liquid precursorcomposition without adverse reaction or of bonding both to the fibre andto the thermoset/thermoplastic composition according to the invention.In particular carbon or graphite fibres that are unsized or are sizedwith epoxy resin precursor or thermoplast such as polyarylsulphone arepreferred. Inorganic fibre preferably is sized with a material thatbonds both to the fibre and to the polymer composition; examples are theorgano-silane coupling agents applied to glass fibre.

The composition may contain for example conventional toughening agentssuch as liquid rubbers having reactive groups, aggregates such as glassbeads, rubber particles and rubber-coated glass beads, filler such aspolytetrafluorethylene, silica, graphite, boron nitride, mica, talc andvermiculite, pigments, nucleating agents, and stabilisers such asphosphates. The total of such materials and any fibrous reinforcingagent in the composition should be at least 20% by volume, as apercentage of the total volume of the polysulphone/thermoset mixture.The percentages of fibres and such other materials are calculated on thetotal composition after curing at the hereinbelow defined temperatures.

The first composition precursor is made by mixing the polysulphone,thermoset precursor and (at some stage) any fibrous reinforcing agentand other materials. A solvent may be present. The solvent and theproportion thereof are chosen so that the mixture of polymer and resinprecursor form at least a stable emulsion, preferably a stableapparently single-phase solution. The ratio of solvent to polysulphoneis suitably in the range 5:1 to 20:1 by weight. Preferably a mixture ofsolvents is used, for example of a halogenated hydrocarbon and analcohol, in a ratio suitably in the range 99:1 to 85:15. Convenientlythe solvents in such a mixture should boil at under 100° C. at 1 atmpressure and should be mutually miscible in the proportions used.Alternatively the polysulphone and thermoset or precursor can be broughttogether by hot melting and/or high shear mixing.

The mixture is stirred until sufficiently homogeneous. Thereafter anysolvent is removed by evaporation to give a concentrated firstcomposition precursor. Evaporation is suitably at 50-200° C. and, atleast in its final stages, can be at subatmospheric pressure, forexample in the range 13.33 Pa to 1333 Pa (0.1 to 10 mm Hg). Theconcentrated first composition precursor preferably contains up to 5%w/w of volatile solvent, to assist flow when used to impregnate fibres.This residual solvent will be removed in contact with the hot rollers ofthe impregnating machine.

The stable emulsion may be stored as appropriate. For further processingthereof, the emulsion must be destabilised to a desired extent,typically by addition of the curing agent in suitable nature and amount,and/or changing temperature and adding or removing solvent. The curingcatalyst component d) is then added. The solution is stirred to ensureuniform distribution of both components and may be cooled and stored asa stable emulsion.

It is an advantage of the present invention that the component d) istypically in the liquid form at or close to room temperature.

The composition of the invention may be cured in known manner. Suitablythe composition in form of a resin solution is transferred onto asuitable mould or tool for preparation of a panel, prepreg or the like,the mould or tool having been preheated to a desired degassingtemperature.

The stable emulsion is combined with any reinforcing, toughening,filling, nucleating materials or agents or the like, and the temperatureis raised to initiate curing thereof. Suitably curing is carried out atelevated temperature up to 150° C., preferably in the range of 100 to130° C., more preferably at about 120-125° C., and with use of elevatedpressure to restrain deforming effects of escaping gases, or to restrainvoid formation, suitably at pressure of up to 10 bar, preferably in therange of 3 to 7 bar abs. Suitably the cure temperature is attained byheating at up to 5° C./min, for example 2° C. to 3° C./min and ismaintained for the required period of up to 9 hours, preferably up to 6hours, for example 3 to 4 hours. Pressure is released throughout andtemperature reduced by cooling at up to 5° C./min, for example up to 3°C./min. Post-curing at temperatures in the range of 150° C. to 180° C.may be performed, at atmospheric pressure, employing suitable heatingrates to improve the glass transition temperature of the product orotherwise.

The concentrated first composition precursor, possibly containing somevolatile solvent already present or newly added, can be used for exampleas an adhesive or for coating surfaces or for making solid structures bycasting possibly in a foamed state. Short fibre reinforcement may beincorporated with composition precursor prior to curing thereof.Preferably a fibre-reinforced composition is made by passing essentiallycontinuous fibre into contact with such precursor composition. Theresulting impregnated fibrous reinforcing agent may be used alone ortogether with other materials, for example a further quantity of thesame or a different polymer or resin precursor or mixture, to form ashaped article. This technique is described in more detail inEP-A-56703, 102158 and 102159.

A further procedure comprises forming incompletely cured compositioninto film by for example compression moulding, extrusion, melt-castingor belt-casting, laminating such films to fibrous reinforcing agent inthe form of for example a non-woven mat of relatively short fibres, awoven cloth or essentially continuous fibre in conditions of temperatureand pressure sufficient to cause the mixture to flow and impregnate thefibres and curing the resulting laminate.

Plies of impregnated fibrous reinforcing agent, especially as made bythe procedure of one or more of EP-A 56703, 102158, 102159, can belaminated together by heat and pressure, for example by autoclave,vacuum or compression moulding or by heated rollers, at a temperatureabove the curing temperature of the thermosetting resin or, if curinghas already taken place, above the glass transition temperature of themixture, conveniently at least 120° C. and typically up to 150° C., andat a pressure in particular in excess of 1 bar, preferably in the rangeof 1-10 bar.

The resulting multi-ply laminate may be anisotropic in which the fibresare continuous and unidirectional, orientated essentially parallel toone another, or quasi-isotropic in each ply of which the fibres areorientated at an angle, conveniently 45° as in most quasi-isotropiclaminates but possibly for example 30° or 60° or 90° or intermediately,to those in the plies above and below. Orientations intermediate betweenanisotropic and quasi-isotropic, and combination laminates, may be used.Suitable laminates contain at least 4 preferably at least 8, plies. Thenumber of plies is dependent on the application for the laminate, forexample the strength required, and laminates containing 32 or even more,for example several hundred, plies may be desirable. There may beaggregates, as mentioned above in interlaminar regions. Woven fabricsare an example of quasi-isotropic or intermediate between anisotropicand quasi-isotropic.

The stable emulsions obtained in the process may have a shelf life longenough to be handled in commerce.

Accordingly there is provided in accordance with the present invention aprocess for the preparation of a curable resin composition comprisingcombining components a) and c) in suitable manner, thereafterincorporating component b) in suitable manner, followed by incorporatingcomponent d), with use of appropriate solvents, diluents, application ofheat and the like as appropriate. Optionally reinforcing orstrengthening agents, fillers and the like may be incorporated insuitable manner.

It should be appreciated that the process may be performed in anydesired sequence, suited to the component and the desired result. Forexample it may be desired to pre-react any two or more components priorto cross-linking with the remaining component(s). However optimumresults are obtained by the employing the sequence as hereinbeforedefined.

In a further aspect of the invention there is provided a compositioncomprising components b) and d) as hereinbefore defined forincorporation with a composition comprising components a) and c) ashereinbefore defined, and any additional materials or agents andinitiating the curing thereof.

Suitably the process as hereinbefore defined is characterised byobtaining a curable resin composition which is adapted to be cured at atemperature below that which would be required for the correspondingcomposition comprising only components a), b) and c) over an equivalentperiod of time, preferably is adapted to be cured at a temperature ofless than that at which the material constituting the mould or tool onor in which it is intended to cure the resin composition becomes heatsensitive in any way, and more preferably at a temperature of less thanor equal to 150° C. at elevated pressure, most preferably at atemperature of less than or equal to 135° C. at a pressure in the rangeof 3 to 7 bar. Suitably the composition is adapted to be cured over aperiod of less than or equal 6 hours, preferably less than or equal to 4hours, most preferably of the order of less than or equal to 3 hours.

In a further aspect of the invention there is provided a process for thepreparation of a cured thermoset resin comprising obtaining the curableresin composition in a suitable mould or tool, or equivalent state inwhich it is to be cured subjecting the composition to a desired curetemperature at suitable pressure, for example at atmospheric pressureand maintaining the temperature for a required period. Preferably thecure temperature is selected as hereinbefore defined, with reference tothe temperature sensitivity of a mould or the like which is beingemployed or otherwise, more preferably is less than or equal to 150° C.at elevated pressure. Preferably the curing time is determined ashereinbefore defined.

In a further aspect of the invention there is provided the use of acomposite mould or tool to contain or support a composition according tothe invention as hereinbefore defined during the curing thereof.Preferably such composite tool is constructed of any suitableunsaturated polyester or thermoset resin such as epoxy or bis-maleinideshaving a heat resistance in excess of the curing temperature to beemployed. Reinforcement is suitably provided in the form of glassfibres. Composite moulds may be prepared in conventional manner for useaccording to the present invention.

In a further aspect of the invention there is provided a prepregcomprising a composition as hereinbefore defined and obtained by aprocess as hereinbefore defined.

In a further aspect of the invention there is provided athermoplast-modified thermoset resin shaped product which is obtained bythe method as hereinbefore defined. Preferably such product is selectedfrom a car, motorbike, caravan or a mobile home panel as hereinbeforedefined or from a furniture component as hereinbefore defined, which isto be made in limited number or for a limited period only. Morepreferably such object is a vehicle body shell, for example, a racingcar body shell.

The invention is now illustrated in non limiting manner with referenceto the following examples.

EXAMPLE 1 Preparation of a Neat Resin Composition of the Invention

A neat resin composition was made in the following manner wherein partsare by weight. 24.8 parts and 25.8 parts respectively of epoxy resincomponents MY0510 and PY306 were weighed into a 500 cm³ tin and warmedto about 40° C. Upon dissolution, 30 parts of thermoplast resincomponent comprising polyarylsulphone of 40:60 PES:PEES ratio, RV 0.26and —NH₂ ends, made according to the procedure given below,pre-dissolved in dichloromethane, was added to the two blended epoxies.The solution was then heated to facilitate the dissolution ofprecipitated polymer. 19.6 parts of catalyst component DDS was thenadded with some additional solvent to aid dispersion. The volume ofsolvent was reduced and 5 parts of titanate curing component (activeweight) was incorporated at this stage in the preparation of the resinsolution.

The polyarylsulphone used in this example was synthesised by reactingtogether the appropriate aromatic dihalo-compounds and dihydric phenolsexemplified by 4,4′-dichlorodiphenyl sulphone (DCDPS) (50 molar parts)with hydroquinone (10 to 40 molar parts) and4,4′-dihydroxydiphenylsulphone (40-10 molar parts) in presence ofpotassium carbonate optionally with sodium carbonate, and diphenylsulphone (DPS) solvent at a temperature rising to 280° C. The synthesisused excess DCDPS and the product thereof was reacted further withm-aminophenol to give amino end groups. The polyarylsulphone wascharacterised by a 40:60 PES : PEES ratio, an RV of 0.26 and amino endgroups.

Compositions were obtained according to the procedure of Example 1 withthe use of the following organotitanates as the curing component ofExample 1, each in an active amount of 5 parts by weight together withadditional solvent as required, as follows:

1a. Tilcom TIPT (tetraisopropyl titanate); 1b. Tilcom IOT (iso octyltitanate); 1c. Tilcom TNBT (Tetra-n-butyl titanate); 1d. Tilcom OGT(Octyleneglycol titanate); 1e. Tilcom TET (Triethanolamine titanate);1f. Tilcom AT23 (Alkanolamine titanate); 1g. Tilcom TAA (Titaniumacetylacetone); 1h. Tilcom IA10 (Titanium chelate solution). 1i TilcomP12 (Titanium acetylacetone (non crystalline)).

EXAMPLE 2

Preparation of a post-cured resin casting according to the invention.The neat resin solution described under Example 1 was poured into a 15cm by 10 cm open cast metal mould, which had been previously heated tothe desired degassing temperature. The resin solution was then degassedfor 45 minutes under vacuum, after which the oven temperature wasincreased to cure temperature of 125° C. and the vacuum removed.

The curing of the resins was monitored every half hour by attempting topierce the surface with a spatula. Curing was determined to have beencompleted when the surface of the resin was considered to have gelled.

The process of Example 2 was carried out with use of the compositions 1ato 1i.

Comparative Example 1

The process of Example 1 was repeated but with the omission of anorganometallic Component d) as hereinbefore defined.

The thus obtained composition was used for the preparation of acomparative neat resin casting according to the process of Example 2using the cure temperature of 125° C. The example was also repeatedusing a cure temperature of 180° C.

The results are given in Table 1 below illustrating the curetemperatures and cure times obtained for compositions 1a to 1i andcomparative example 1.

TABLE 1 Amount of Titanate Resin (125° C.) used (parts wt) Cure Time(hours) 1e 6.25 3 1a 5.0 4 1d 5.0 >15 1c 5.0 5 1g 6.66 2.5 1b 5.0 >15 1h7.6 4 1f 7.24 6.5 Comp. Ex 1 125° C. — >18 Comp. Ex 1 180° C. — 3

In Table 1 the amount of titanate used is calculated to give an activeamount of 5 parts by weight with respect to the titanium constituent.

From Table 1 is apparent that the compositions of the present inventionare superior to those of the comparative example, in most cases showinga dramatic improvement in cure time which would be of enormousindustrial potential.

The cured products obtained with examples 1e, 1f and 1g moreover showedfinished quality which were comparable to or indistinguishable fromthose of the corresponding comparative example cured at elevatedtemperature according to known practices.

EXAMPLE 3

The process of Example 2 was repeated with use of the compositions 1e,1f and 1g but using varied amount of the respective organometalliccomponent d). The resulting compositions were cured at a temperature of125° C. according to the process of Example 2 and the variation in timeto cure the neat resin panel was monitored. The results are shown inTable II.

TABLE II Amount of Titanate Resin Used (parts wt) Cure Time (hours) 1e3.5 4 1e 6.25 3 1e 9.0 2.5 1f 4.5 3.5 1f 6.66 2.5 1f 9.0 2.25 1g 5.0 >151g 7.24 6.5 1g 10.0 6

EXAMPLE 4

The process of Example 2 was repeated employing compositions 1e, 1f, 1gand the Comparative Example but varying the cure time employed in orderto determine the various mechanical and thermal properties thereof. Theresults are shown in Tables III and IV.

TABLE III Resin/Parts wt. Cure Time (Hours) Tg (onset) ° C. Comp.Ex1/- >18 hours 127 1f/9 6 105 1g/6.66 6 139 1g/6.66 6 138 1e/9 6 133 1e/93 105

TABLE III Resin/Parts wt. Cure Time (Hours) Tg (onset) ° C. Comp.Ex1/- >18 hours 127 1f/9 6 105 1g/6.66 6 139 1g/6.66 6 138 1e/9 6 133 1e/93 105

From Table III it is apparent that the glass transition temperaturecould be influenced by appropriate selection of Component d) and ofcuring time. Advantageously the glass transition temperature (Tg) couldbe decoupled from the curing temperature with selection of suitablecomponents d), the neat cured resin of compositions 1e and 1g showing aTg of 133° C. and 139° C. respectively after curing for 6 hours at 125°C. of the composition comprising 9.0 and 6.66 parts of component d)respectively.

From Table IV it is apparent that variation in the cured resinmechanical properties of yield stress, modulus, K_(c). G_(c) andductility were typical of the Component d) employed and showed littlevariation with the cure time variation, indicating that curing wassubstantially complete in the shorter period employed and that theproperty showed little or no deterioration when subjected to continuedheat.

EXAMPLE 5

The morphology of the compositions was determined employing TEM by knownmanner. Morphologies were classed as co-continuous, phase inverted andcombinations thereof with corresponding effect on the toughness of thecured resins. FIGS. 1 and 2 illustrate the morphology of comparativeexample 1 and of composition 1e according to the invention respectively.It will be apparent that the incorporation of Component d) has inducedno change with respect to the co-continuous morphology of the resin ofcomparative example 1, however additional attractive features areinduced by the microstructure included therein of the phase invertedtype.

EXAMPLE 6 Preparation of a Prepreg of the Composition of the Invention

A solution containing epoxy formulation comprising 24.8 and 25.8 partsrespectively of components MY0510 and PY306 and (on total solids) 30parts of polyarylsulphone of 40:60 PES : PEES ratio, RV 0.26 and —NH₂ends, in methylene chloride at 55% w/w solids content is made bymelt-mixing the two epoxy resin precursors at 50-80° C., adding, withstirring, a solution of the polyarylsulphone in methylene chloride. Itis heated at 80-120° C. to remove excess solvent and obtain a clearsolution. 19.6 parts of the curing agent, DDS, is then added and stirredin until uniformly distributed, and 6.66 parts of titanate curingcomponent, comprising an equivalent active weight of 5 parts, is thenadded. The resulting viscous liquid mixture is cooled and stored at 0°C. until required for use.

Unsized continuous collimated carbon fibres (available as grade AS4Hercules Inc) are impregnated with this solution and the solventevaporated to produce prepreg tape of resin content 36% w/w and lessthan 1% w/w volatiles. The prepreg is moulded in an autoclave intopanels with appropriate lay-up using a standard vacuum bag technique andthe following cure cycle:

heat to 125° C. at 2° C./min at a pressure held between 3 and 7 bar abs;

hold 6 h at 125° C. under pressure held between 3 and 7 bar abs whilstventing vacuum bag;

cool to room temperature at less than 3° C./min.

Cured composites were obtained according to the procedure of Example 6with use of the following organotitanates as curing component of Example6:

6e Tilcom TET (Triethanolamine titanate)

6g Tilcom TAA (Titanium acetylacetone)

6i Tilcom P12 (Titanium acetylacetone (non crystalline))

Comparative Example 2

The procedure of Example 6 was followed but with the omission of anorganometallic Component d) as hereinbefore defined, to obtain acomparative cured composite not according to the invention.

EXAMPLE 7

The process of Example 6 was repeated employing the composites 6e and 6ibut varying the amount of titanate used and cure time employed in orderto determine various mechanical and thermal properties thereof.

Mechanical and thermal properties of unidirectional composites weredetermined. Composites were subject to curing using conditions of 125°C. for five hours (hereinafter cure 1) and test data obtained.Composites were further subject to a post-cure at 180° C. for two hours(hereinafter cure 2) and further test data obtained. The results areshown in Table V and VI.

TABLE V Composite/ Modulus (GPa) TFS (MPa) SBS(MPa) Parts wt. Cure 1Cure 2 Cure 1 Cure 2 Cure 1 6i/1 78.05 83.2 36.40 58.81 48.95 6i/3 80.3— 39.96 58.63 69.27 6i/5 79.45 85.9 37.71 70.17 89.6 6e/3 77.4 83.3 32.180.57 40.56 Comp. 78.82 90.5 29.01 83.83 40.32 Ex2./-

TABLE V Composite/ Modulus (GPa) TFS (MPa) SBS(MPa) Parts wt. Cure 1Cure 2 Cure 1 Cure 2 Cure 1 6i/1 78.05 83.2 36.40 58.81 48.95 6i/3 80.3— 39.96 58.63 69.27 6i/5 79.45 85.9 37.71 70.17 89.6 6e/3 77.4 83.3 32.180.57 40.56 Comp. 78.82 90.5 29.01 83.83 40.32 Ex2./-

TFS (Trans Flexural Strength) and SBS (Short Beam Shear) values indicatethat both interfacial bonding and cohesive strength of the matrix resinsare low. Values of between 40-50 MPa SBS suggest a weak interface bond(leading to inter laminar cracking) and low toughness matrix resins.This is attributed to the fact that the composites subject to cure 1 areincompletely cured. Notably the comparative example and composition 6ehave low SBS values. As the amount of titanate in compositions 6iincreases, so then does the value of SBS, suggesting an increase ininter laminar toughness in these systems.

The results therefore show that the compositions 6i have reached agelation point after cure 1 much more rapidly than those of thecorresponding Comparative Example 2.

The modulus values obtained from all the samples are similar.

With reference to modulus and TFS values after cure 2 it is clear thatthe modulus in all cases has increased suggesting that the cross-linkeddensity has increased on post-curings. TFS values are also substantiallyhigher in all cases, again suggesting that degree of cure andcross-linked density have greatly increased during post-cure. Thisincrease in the degree of cure will improve both the cohesive strengthof the matrix and the fibre matrix interfacial bond.

Accordingly it is apparent that the compositions of the invention aresuited for first and second stage curing and post-curing in manner toprovide cured systems having favourable mechanical properties. Notableis the intermediate properties obtained after cure 1 which infer thatcompositions of the invention have gelled sufficiently to be removedfrom the autoclave and subject to post-cure in standard atmosphericpressure curing apparatus. In contrast the compositions of thecomparative examples are insufficiently gelled to enable removal fromthe autoclave without deterioration of the structure of the resin orcomposite.

With reference to Table VI the glass transition temperature (Tg) wasdetermined by use of DMTA on composite systems cured at 125° C. for fivehours. The compositions of the invention exhibit higher Tg than theuncatalysed Comparative Example 2. In general however the Tg results,with the possible exception of composition 6i/5, are low. This agreeswith the previous data and suggests incomplete cure and a low degree ofcross-linking in the epoxy network.

Moreover it would seem that variation in the post-cured resin mechanicalproperties of TFS were typical of the Component d) employed and showedlittle variation with the amount of component d), indicating that curingwas substantially complete in the combined pre-cure and non-autoclavepost-cure period. Post-cured properties of modulus showed little or nodeterioration when compared to the comparative example cured under sameconditions, indicating satisfactory suitability for commercialapplication.

It is therefore apparent that the glass transition temperature can beinfluenced by appropriate selection of nature and amount of Component d)and of curing time. Advantageously the glass transition temperature (Tg)can be decoupled from the curing temperature with selection of suitablecomponents d), the neat cured resin 6i showing a variation in Tg of some20° after curing for 5 hours at 125° C. of the composition comprising 1to 5 parts (wt) of component d) respectively.

EXAMPLE 8

The morphology of the compositions of the previous examples wasdetermined employing TEM by known manner. Morphologies were classed asco-continuous, phase inverted and combinations thereof withcorresponding effect on the toughness of the cured resins. FIGS. 1 and 2illustrate the morphology of Comparative Example 2 and of Composition 6eaccording to the invention respectively. SEM indicates that theincorporation of Component d) has induced no change with respect to theco-continuous morphology of the resin of composition 6i/1 when comparedto the Comparative Example 2, however additional attractive mechanicalfeatures are induced by the microstructure included therein of the phaseinverted type.

The morphologies of the 3 and 5 parts by weight systems of compositions6i are all phase inverted with the thermoplastic rich phase beingcontinuous. This seems to comprise a morphology of epoxy rich particlesin a continuous thermoplastic rich phase. In these systems thecontinuous thermoplastic rich phase tends to dominate the mechanicalproperties of the matrix. This results in low modulus and a low cohesivestrength of the matrix. Phase inverted morphologies also show poorenvironmental resistances to solvents.

It should be noted however that the advance in mechanical properties ofthe compositions when subject to cure 2 may therefore be influential inadvancing and improving also their morphology. Accordingly it would seemthat the ability to post-cure the compositions of the invention in afree standing oven at atmospheric pressure may be carried out withoutdisrupting the development of morphology.

Accordingly, it will be apparent that the compositions according to theinvention as hereinbefore defined and according to the Examples areeminently suited for casting in composite moulds having a heatresistance of greater than 180° C. over a period of up to five hoursand/or of 125° C. over a prolonged period of up to 15 hours, for examplefor up to 5 hours. This represents a novel feature of the invention.

What is claimed is:
 1. A curable composition comprising: (a) a thermosetresin component having reactive pendant and/or end groups; (b) a curingagent component; (c) an amount of a thermoplast component havingreactive pendant and/or end groups; and (d) an organometallic curingcatalyst component, wherein Component (d) is capable of formingcross-links with reactive pendant and/or end groups of the thermoset andthermoplast resins, and comprises an organometallic complex compound ofthe formula I: M(R)_(n)  (I) wherein M is selected from titanium,zirconium, hafnium, cerium, vanadium, niobium, R is selected from mono-,bi- and tri and/or tetra dentate organic ligands and n is four or six,and wherein the composition is capable of being pre-cured to a gelledstate, at elevated temperature up to 150° C. and post cured at elevatedtemperature up to 180° C., in a manner to advance mechanical propertiesto obtain higher Tg and improve morphology.
 2. The curable compositionaccording to claim 1, wherein Component (c) comprises at least onethermoplastic polyaryl sulphone component.
 3. The curable compositionaccording to claim 1, wherein Component (c) comprises at least onepolyaryl sulphone comprising ether-linked repeating units, optionallyadditionally comprising thioether-linked repeating units, the unitsbeing selected from the group consisting of —(PhSO₂Ph)_(n)— andoptionally additionally —(Ph)_(a)— wherein Ph is phenylene, n=1 to 2 andcan be fractional, a=1 to 3 and can be fractional and when a exceeds 1,said phenylenes are linked linearly through a, single chemical bond or adivalent group other than —SO₂— or are fused together, provided that therepeating unit —(PhSO₂Ph)_(n)— is always present in said at least onepolyarylsulphone in such a proportion that on average at least two ofsaid units —(PhSO₂Ph)_(n)— are in sequence in each polymer chainpresent, said at least one polyarylsulphone having reactive pendantand/or end groups of formula —A′Y where A′ is a divalent hydrocarbongroup and Y is a group selected from groups providing active hydrogen,epoxy, cyanate, isocyanate, vinyl, allyl, ethynyl and maleimidefunctionality.
 4. The curable composition according to claim 3, whereinthe relative proportions of the said repeating units is such that onaverage at least two units (PhSO₂Ph)_(n) are in immediate mutualsuccession in each polymer chain present and is in the range 1:99 to99:1 respectively.
 5. The curable composition according to claim 3,wherein the units are: 1 X Ph SO₂ Ph X Ph SO₂ Ph (“PES”) and 11 X (Ph)aX Ph SO₂ Ph (“PEES”) where X is O or S and may differ from unit to unit;the ratio of 1 to 11 (respectively) between 10:90 and 80:20.
 6. Thecurable composition according to claim 2, wherein the polyaryl sulphonecontains up to 50% molar of other repeating units.
 7. The curablecomposition according to claim 2, wherein the number average molecularweight of the polyaryl sulphone is in the range 2000 to
 60000. 8. Thecurable composition according to claim 1, wherein Component (a) isselected from the group consisting of an epoxy resin, anaddition-polymerization resin, a formaldehyde condensate resin, acyanate resin, an isocyanate resin and mixtures of two or more thereof.9. The curable composition according to claim 1, wherein Component (a)is an epoxy resin derived from a mono or poly-glycidyl derivative of oneor more of the group of compounds consisting of aromatic diamines,aromatic monoprimary amines, aminophenols, polyhydric phenols,polyhydric alcohols, polycarboxylic acids, and mixtures thereof.
 10. Thecurable composition according to claim 1, wherein Component (b)comprises an amino compound having a molecular weight up to 500 peramino group.
 11. The curable composition according to claim 1, wherein Mis selected from titanium and zirconium.
 12. The curable compositionaccording to claim 11, wherein Component (d) comprises at least in part,an amount of compound of formula I which has been pre-reacted to formmultinuclear complex, oligomeric or combination products.
 13. Thecomposition as claimed in claim 1, wherein R is independently organicligands comprising one or more nucleophilic units or moieties, selectedfrom straight or branched, short or long chain alcohols, amines, acids,esters, phosphates, ketones and anhydrides which may optionally beadditionally functionalized, and combinations thereof.
 14. The curablecomposition according to claim 1, wherein R is a combination ofmonodentate ligands with one or more bi, tri or tetradentate ligands,and is selected from glycols, alkanolamines, alpha-hydroxy acids,-keto-esters and acid phosphates and combinations thereof.
 15. Thecurable composition according to claim 14, wherein Component (d)comprises an organo titanate wherein two of the organic ligands comprisemonodentate ligands and a further two comprise bidentate chelateligands, wherein the ligands may be present in any combination ofmultiplicity and type.
 16. The composition as claimed in claim 14,wherein the component (d) includes one or more organotitanates of theformula II: Ti(R′)₄  (II) wherein R′ is selected from organic ligandsoptionally in combination with one or more bidentate ligands selectedfrom glycols, alcohol amines, alphahydroxy acids, -ketone esters andacid phosphates.
 17. The curable composition according to claim 16,wherein the Component (d) comprises one or more monodentate ligandsselected from alcohols and amines optionally in combination with one ormore bidentate ligands selected from glycols, alcohol amines,alphahydroxy acids, -ketone esters and acid phosphates.
 18. The curablecomposition according to claim 1, wherein said composition furthercomprises a fibre reinforcement.
 19. The curable composition accordingto claim 1, said composition further comprising a toughening agentselected from liquid rubbers having reactive groups, aggregates, glassbeads, rubber particles and rubber-coated glass beads, filler selectedfrom polytetrafluorethylene, silica, graphite, boron nitride, mica, talcand vermiculite, pigments, nucleating agents, and stabilizers.
 20. Thecurable composition according to claim 1, wherein said composition iscast in a mold to support the composition during the curing thereof, andwherein the mold is constructed of a thermoset material having heatresistance in excess of the curing temperature to be employed.
 21. APre-preg comprising a curable composition comprising: (a) a thermosetresin component having reactive pendant and/or end groups; (b) a curingagent component; (c) an amount of a thermoplast component havingreactive pendant and/or end groups; (d) an organometallic curingcatalyst component; and (e) a continuous fibre reinforcement, whereinthe Component (d) is capable of forming cross-links with reactivependant and/or end groups of the thermoset and thermoplast resins, andcomprises an organometallic complex compound of the formula I:M(R)_(n)  (I) wherein M is selected from titanium, zirconium, hafnium,cerium, vanadium, niobium, R is selected from mono-, bi- and tri and/ortetra dentate organic ligands and n is four or six, and wherein thecomposition is capable of being pre-cured to a gelled state, at elevatedtemperature up to 150° C. and post cured at elevated temperature up to180° C., in a manner to advance mechanical properties to obtain higherTg and improve morphology.
 22. The pre-preg according to claim 21,wherein said pre-preg is cured.
 23. The pre-preg according to claim 21,wherein said pre-preg is a shaped product.
 24. A process for thepreparation of a curable composition for a composite comprising: (a) athermoset resin component having reactive pendant and/or end groups; (b)a curing agent component; (c) an amount of a thermoplast componenthaving reactive pendant and/or end groups; and (d) an organometalliccuring catalyst component, wherein Component (d) is capable of formingcross-links with reactive pendant and/or end groups of the thermoset andthermoplast resins, and comprises an organometallic complex compound ofthe formula I: M(R)_(n)  (I) wherein M is selected from titanium,zirconium, hafnium, cerium, vanadium, niobium, R is selected from mono-,bi- and tri and/or tetra dentate organic ligands and n is four or six,and wherein the composition is capable of being pre-cured to a gelledstate, at elevated temperature up to 150° C. and post cured at elevatedtemperature up to 180° C., in a manner to advance mechanical propertiesto obtain higher Tg and improve morphology, said process comprising thesteps of: (1) admixing the components (a), (b), (c) and any optionallyadditional materials; and (2) combining the result of step 1 withComponent (d).
 25. A process for the preparation of a curablecomposition for a composite comprising: (a) a thermoset resin componenthaving reactive pendant and/or end groups; (b) a curing agent component;(c) an amount of a thermoplast component having reactive pendant and/orend groups: and (d) an organometallic curing catalyst component, whereinComponent (d) is capable of forming cross-links with reactive pendantand/or end groups of the thermoset and thermoplast resins, and comprisesan organometallic complex compound of the formula I: M(R)_(n)  (I)wherein M is selected from titanium, zirconium, hafnium, cerium,vanadium, niobium, R is selected from mono-, bi- and tri and/or tetradentate organic ligands and n is four or six, said process comprisingthe steps of: (1) subjecting said composition to a first elevatedtemperature up to 150° C. and elevated pressure to a gelled state; and(2) post-curing at a second elevated temperature up to 180° C. andatmospheric pressure in a manner to advance mechanical properties ofsaid composition to obtain higher Tg and improve morphology.
 26. Theprocess according to claim 25, wherein said composite is a shapedarticle, and wherein curing of said composite is carried out while incontact with or contained in a suitable support.
 27. The processaccording to claim 26, wherein said support is able to maintain itsmolding integrity at temperatures not substantially exceeding 180° C.28. The process according to claim 25, wherein said first elevatedtemperature is at an elevated temperature in the range of 100-130° C.,and post-curing at a second elevated temperature is at temperatures inthe range of 150-180° C.